Circuit board device for information apparatus, multilayered module board and navigation system

ABSTRACT

A multilayered module board with mounted high-frequency electronic components such as a CPU and a graphic circuit is mounted on one face of a base board with mounted low-frequency electronic components. The multilayered module board is a squared multilayered board smaller than the base board. The electronic components are wired with an inner layer-wiring pattern. Connector terminals are solder-jointed to four sides of the multilayered module board. The multilayered module board is mounted to the base board via the connector terminal.

INCORPORATION BY REFERENCE

The disclosure of the following priority application is hereinincorporated by reference:

-   Japanese Patent Application No. 2002-106513

TECHNICAL FIELD

The present invention relates to a circuit board structure in aninformation apparatus ideal in applications such as an on-vehicleinformation terminal having a navigation function.

BACKGROUND ART

There are on-vehicle information terminals in the known art, that havenavigation functions including a function for displaying a road map ofan area around the current vehicle position, a function for determininga recommended route from a start point to a destination througharithmetic operation and a function for providing route guidance basedupon the recommended route determined through the arithmetic operation.

Such an on-vehicle information terminal includes a navigation circuitboard. The navigation circuit board is achieved by mounting on a singlemultilayer printed board a plurality of low-frequency electroniccomponents such as a power circuit, a gyro, a GPS circuit and aplurality of high-frequency electronic components such as a CPU chip, amemory chip and a graphics chip.

Since the navigation specifications vary among different vehicle models,the navigation circuit board is designed and manufactured in conformanceto each set of specifications in the related art. This means a greatlength of time must be spent in the design stage to result in highproduction costs, and it is naturally more desirable to use fewer typesof more versatile navigation circuit boards. Such a need is not uniqueto navigation circuit boards, but it is a common concern pertaining toall types of information terminals including on-vehicle informationterminals, in which a given function needs to be altered for differentmodels.

The present invention provides a circuit board structure to be adoptedin an information apparatus that eliminates the need to design andmanufacture the circuit board from scratch for each set ofspecifications.

DISCLOSURE OF THE INVENTION

The circuit board device for an information apparatus according to thepresent invention comprises a base board having a plurality ofelectronic components mounted thereupon and a multilayer module boardmounted at one surface of the base board and having mounted thereupon aplurality of electronic components including at least a CPU and amemory. The multilayer module board is a multilayered board smaller insize than the base board, and the plurality of electronic components arewired through a wiring pattern at an inner layer of the multilayerboard.

The multilayer module board may be connected to the base board bysoldering a connector terminal provided at a peripheral edge thereofonto a junction portion formed on the base board.

It is desirable to mount an electronic component at another surface ofthe multilayer module board by utilizing a space formed by the connectorterminal between the multilayer module board and the base board inaddition to the electronic components mounted at one surface of themultilayer module board.

It is desirable to mount low-frequency electronic components at the baseboard and mount high-frequency electronic components at the multilayermodule board.

The high-frequency electronic circuits include at least a graphicscircuit as well as the CPU and the memory. In addition, thelow-frequency electronic circuits include at least a power circuit, agyro and a GPS circuit. The circuit board device described above may beadopted in a navigation system.

At the multilayer module board according to the present invention, aplurality of high-frequency electronic components including the CPU andthe memory are mounted at, at least, a surface thereof on one side, andthe plurality of high-frequency electronic components are connected withone another through a wiring pattern formed at an inner layer. Theoverall shape of this module board may be rectangular. Connectorterminals provided as separate members may each be connected throughsoldering onto one of the four peripheral edges of the board. The fourconnector terminals at such a multilayer module board each include anarrow elongated base portion constituted of resin and a plurality ofpins fixed to the base portion and the four connector terminals arecarried with the base portions mounted at a transfer adapter and areconnected through soldering onto the rear surface of the board whileattached to the transfer adapter.

The multilayer module board may adopt the structure described below. Thefour connector terminals may each include a narrow, elongated baseportion constituted of resin, a plurality of pins fixed to the baseportion, aligning pins projecting at both ends of the base portion to beused when soldering the connector terminal onto the rear surface of theboard, and inclined surfaces for position control formed at both ends ofthe base portion to be used when soldering the connector terminal. Ateach of the four corners of the board, a pair of positioning holes atwhich the aligning pins can be loosely fitted may be formed. Thisstructure allows the position control inclined surfaces of adjacentconnector terminals to come into contact with each other in a state inwhich the aligning pins are loosely fitted at the positioning holes, andthus, it becomes possible to control the positions of the connectorterminals when connecting them to the board through soldering.

The circuit board for the navigation system according to the presentinvention adopts the following structure. Module boards include, atleast, a high-speed module board, an advanced function module board, alow-end module board and a multimedia module board having anon-navigation function that allows various types of data such as musicand images to be reproduced as well as a navigation function. A singlecommon base board can be used in conjunction with a plurality of moduleboards and the circuit board is manufactured by mounting one moduleboard selected from the plurality of module boards at the base board.

The high-speed module board is a circuit board for a high-gradenavigation system that operates at higher speed rather than a navigationsystem conforming to low-end specifications. The advanced functionmodule board is a circuit board for a high-grade navigation systemhaving more functions than a navigation system conforming to low-endspecifications. The low-end module board is a circuit board for a lessexpensive navigation system conforming to lower end specificationsrather than the high-grade navigation system.

According to the present invention described above, the need to designand manufacture a circuit board for each set of specifications fromscratch is eliminated and thus, the length of time to be spent in thedevelopment stage is reduced to achieve a cost reduction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system block diagram presenting an example of a navigationsystem in which the circuit board device for an information apparatusaccording to the present invention may be adopted;

FIG. 2 is a perspective of the circuit board device for an informationapparatus achieved in an embodiment of the present invention;

FIG. 3 shows the front surface of the circuit board device in FIG. 2;

FIG. 4 shows the rear surface of the circuit board device in FIG. 2;

FIG. 5 is a sectional view taken a long line V-V in FIG. 3;

FIG. 6 shows the rear surface of the multilayer module board in FIG. 2;

FIG. 7 shows the transfer adapter attached to the rear surface of themultilayer module board in FIG. 2;

FIG. 8 shows in an enlargement an essential portion of a corner area atthe rear surface of the multilayer module board in FIG. 2;

FIG. 9 is a perspective showing the transfer adapter mounted at thecircuit board device in FIG. 2;

FIG. 10 is a perspective showing in an enlargement an essential portionof a corner area of the transfer adapter; and

FIG. 11 is a sectional view of the structure adopted to position theconnector terminals and the multilayer module board relative to eachother.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a system block diagram of a navigation system 10 achieved inan embodiment of the present invention. The navigation system 10 hasfunctions for providing information related to vehicle travel. Morespecifically, it has a function for displaying a road map of an areaaround the current vehicle position, a function for calculating arecommended route from the start point (the current position) to adestination (an end point) through arithmetic operation, a function forproviding route guidance based upon the calculated recommended route andthe like. In short, it is an apparatus that provides so-callednavigation or route guidance.

Reference numeral 11 in FIG. 1 indicates a current position detectiondevice that detects the current position of the vehicle, which mayinclude, for instance, a gyro 11 a that detects the advancing directionof the vehicle, a vehicle speed sensor 11 b that detects the vehiclespeed and a GPS circuit 11 c that detects a GPS signal provided from aGPS satellite. Reference numeral 12 indicates a map storage memory inwhich road map data, address data and the like readout by a read devicefrom a recording medium such as a CD-ROM 13 or a DVD are stored asneeded.

Reference numeral 14 indicates a control circuit that controls theoverall system and comprises a microprocessor and its peripheralcircuits. The control circuit 14 uses a RAM 15 as a work area where itimplements various types of control to be detailed later by executing acontrol program stored in a ROM 16. Reference numeral 17 indicates agraphics circuit that executes, for instance, drawing processing whendisplaying a planimetric map, a stereoscopic map (a birds-eye-view map)or the like at a monitor 19.

Reference numeral 18 indicates an image memory in which image data to bedisplayed at the display monitor 19 are stored. The image data, whichinclude road map drawing data and various types of graphics data, areprepared at the graphics circuit 17. The image data stored in the imagememory 18 are read out as needed and are displayed at the displaymonitor 19. Reference numeral 20 indicates an ASIC that executesprocessing such as a route search calculation.

The navigation system 10 adopting the structure described above executesa route search by designating the subject vehicle position detected bythe current position detection device 11 as the start point anddesignating the destination set by the operator as the end point. Theroute search is executed by adopting a method of the known art basedupon the road map data stored in the CD-ROM 13 or the map storage memory12. The route resulting from the search is displayed with a bold line onthe display monitor 19 and the vehicle is guided to the destination byproviding audio guidance whenever the vehicle approaches a right or leftturn point.

FIG. 2 is a perspective of a circuit board device 100 of the navigationsystem 10, FIG. 3 shows the circuit board device 100 viewed from thefront and FIG. 4 shows the circuit board device 100 viewed from therear. The circuit board device 100 includes a multilayer base board 200having a plurality of electronic components mounted thereupon and amultilayer module board 300 mounted at the base board 200 and havingmounted thereupon a plurality of electronic components including atleast a CPU and a memory. The multilayer module board 300 is connectedto the base board 200 by soldering connector terminals 310 disposed atperipheral edges thereof to junction portions formed at the base board200.

A plurality of wiring pattern layers are formed in the base board 200,and a power device 201, a GPS circuit 202, a gyro 203 and otherelectronic components are mounted at the top layer (the front surface)of the base board 200. At the bottom layer (the rear surface) of thebase board 200, connector devices 204 and other electronic componentsare mounted. The electronic components mounted at the base board 200 areall low-frequency components connected with one another through thewiring patterns formed at inner wiring pattern layers. It is to be notedthat while electronic components having operating frequencies equal toor lower than 40 MHz are defined as the low-frequency electroniccomponents in the explanation of the embodiment, low-frequencyelectronic components may operate at other operating frequencies.

The multilayer module board 300 assuming a square shape includes aplurality of wiring pattern layers. A plurality of high-frequencyelectronic components such as a CPU 301, an ASIC 302, a memory 303, agraphics circuit 304 and a flash memory 305 are mounted at the top layer(the front surface) of the multilayer module board 300. In thisembodiment, the CPU 301, the ASIC 302, the memory 303, the graphicscircuit 304 and like with operating frequencies equal to or higher than200 MHz are provided in a so-called multi-chip module. These high-speedelements are connected with one another through a wiring pattern formedat an inner layer of the multi-chip module. The operating frequencies ofelements that are not part of the multi-chip module, such as the flashmemory 305, are equal to or higher than 100 MHz and equal to or lowerthan 200 MHz, and these elements are connected with one another at aninner pattern layer in the multilayer module 300. It is to be noted thatthe high-frequency electronic components may operate at operatingfrequencies other than those mentioned above.

By wiring the high-frequency electronic components at the inner patternlayers in the multi-chip module and the multilayer module board 300, thelength of the wiring required to connect the high-frequency electroniccomponents can be reduced compared to the length of wiring that would berequired to connect them all at the front surface of the multilayermodule board 300, which will approve effective when adopted inconjunction with EMI. It is to be noted that while electronic componentsthat operate at operating frequencies equal to or higher than 100 MHzare defined as high-frequency electronic components in the explanationof the embodiment, the high-frequency electronic components may operateat other frequencies.

As shown in FIG. 5, a specific clearance (space) is formed by theconnector terminals 310 between the rear surface of the multilayermodule board 300 and the base board 200. By effectively utilizing thisspace, a plurality of electronic components 320, 321, . . . can bemounted at the bottom layer (rear surface) of the multilayer moduleboard 300.

FIG. 6 is a bottom view of the multilayer module board 300. As shown inFIG. 6, connector terminals 310 a to 310 d (they may be collectivelyreferred to by using reference numeral 310) are each connected throughsoldering to one of the four sides at the rear surface of the multilayermodule board 300. In this embodiment, the connector terminals 310 a to310 d are attached to a transfer adapter 400, as shown in FIG. 7, themultilayer module board 300 is handled by vacuum holding the transferadapter 400 with a handling device, and the multilayer module board 300is then soldered onto the base board 200. The transfer adapter 400 isalso used when connecting through soldering the connector terminals 310a to 310 d to the multilayer module board 300 to improve the ease of thesoldering operation. The transfer adapter 400 is to be detailed later.

In reference to FIG. 6 and to FIG. 8, which shows in detail a corner ofthe rear surface of the multilayer module board 300, the connectorterminals 310 are explained. The four connector terminals 310 eachinclude a narrow, elongated base portion 311 constituted of resin, aplurality of pins 312 fixed onto the base portion 311, aligning pins 313(see FIG. 11) each projecting at the front surface of the base portion311 at one of the two ends thereof, i.e., on the reverse side of theview shown in FIG. 8, to be used when soldering the connector terminalonto the rear surface of the board, inclined surfaces 314 for positioncontrol each formed at one of the two ends of the base portion 311 to beused when connecting the connector terminal through soldering, fittingconnection portions 315 and 316 each located at one of the two ends ofthe base portion 311 to connect with the transfer adapter 400 andconnecting grooves 317 at which positioning projections 411 (see FIG. 9)of the transfer adapter 400 are inserted.

As shown in FIG. 7, the transfer adapter 400 includes an outer perimeterportion 410 substantially assuming the shape of a closed rectangle and across portion assuming a cross shape that connects the sides of theouter perimeter portion 410 to one another. FIG. 9 is a perspective of acorner area of the transfer adapter 400. As shown in FIG. 9, at a cornerof the outer perimeter portion 410, a projection 411 that is inserted inconnecting grooves 317 of connector terminals 310, outer connectionclaws 412 which connect with the fitting connection portion 315 of aconnector terminal 310 and inner connection claws 413 which connect withthe fitting connection portion 316 of a connector terminal 310 areprovided.

At each of the four corners of the multilayer module board 300, a pairof positioning holes 306 at which the aligning pins 313 of themultilayer module board 300 are loosely fitted are formed.

As shown in FIG. 10, as the fitting connection claws 412 (413) at thetransfer adapter 400 become engaged with the fitting connecting portions315 (316), the four connector terminals 310 each become snapped onto thetransfer adapter 400. While the widthwise movement of the connectorterminals 310 having become snapped onto the transfer adapter 400 isrestricted inside the transfer adapter 400, they are held with a degreeof freedom of movement along other directions. The transfer adapter 400is handled with a transfer device, the transfer adapter 400 ispositioned in this state onto the rear surface of the multilayer moduleboard 300 and the connector terminals 310 are then soldered onto themultilayer module board 300.

The aligning pins 313 in the connector terminals 310 are designed so asto have a predetermined degree of play relative to the positioning holes306 at the multilayer module board 300. Thus, by manipulating thetransfer adapter 400, the aligning pins 313 of the connector terminals310 are fitted into the positioning holes 306 at the multilayer moduleboard 300, as shown in FIG. 11. The connector terminals 310 are solderedonto the multilayer module board 300 in this state. Since the pins 313are fitted in the holes 306 with play, the connector terminals 310attached to the transfer adapter 400 may still move inside the transferadapter 400. However, the positions of the connector terminals 310 arecontrolled in the embodiment as the position control inclined surfaces314 of, for instance, the adjacent connector terminals 310 b and 310 ccome into contact with each other, as shown in FIG. 8. As a result, theconnector terminals 310 are positioned at the individual sides of themodule board 300 within an allowable range and the connector terminals310 are connected through soldering onto the multilayer module board 300via the pins 312 in this state.

As shown in FIG. 7 referred to earlier, such a module board 300 isconnected through soldering onto the base board 200 together with otherelectronic components by vacuum holding the transfer adapter 400attached to the connector terminals 310 a to 310 d with the handlingdevice.

The following advantages are achieved by using the circuit board devicedescribed above.

-   (1) Navigation systems with various functions can be manufactured    simply by using interchangeable multilayer module boards 300. For    instance, a high-speed module board, an advanced function module    board, a low-end module board, a multimedia module board and the    like may each be designed and manufactured to be utilized as a    multilayer module board 300, so as to achieve circuit board devices    for navigation systems conforming to different sets of    specifications with ease at a low production costs simply by    mounting specific types of multilayer module boards 300 selected for    specific purposes at the base board 200. Namely, it becomes no    longer necessary to design and manufacture the entire circuit board    device for each set of specifications.

It is to be noted that the high-speed module board is a circuit boardfor a high-end navigation system that operates at higher speed ratherthan a navigation system conforming to low-end specifications. Theadvanced function module board is a circuit board for a high-endnavigation system having more functions than a navigation systemconforming to low-end specifications. The low-end module board is acircuit board for a less expensive navigation system conforming tolower-end specifications rather than a high-end navigation system. Themultimedia module board is a circuit board for a navigation systemhaving a function of reproducing various types of data such as music andimages in addition to a navigation function.

-   (2) The multilayer module board 300 is connected to the base board    200 by soldering the connector terminals 310 disposed at its    peripheral edges to junction portions formed on the base board 200.    Thus, compared to a connecting structure achieved by using    mechanical connectors, a more reliable structure which is less prone    to contact failure caused by vibration is achieved.-   (3) Additional electronic components can be mounted at the rear    surface of the multilayer module board 300 by effectively utilizing    the space formed by the connector terminals 310 between the base    board 200 and the multilayer module board 300. This improves the    mounting efficiency and the circuit board device can be provided as    a more compact unit.-   (4) High-frequency electronic components are connected with one    another through wiring patterns formed at inner layers of the    multi-chip module and the multilayer module board. Since this    reduces the length of the wiring, the extent of signal delay can be    minimized and, at the same time, the occurrence of noise can be    minimized, as well.-   (5) Low-frequency electronic components are mounted at the base    board 200, whereas high-frequency electronic components are mounted    at the multilayer module board 300. This facilitates the    implementation of EMI measures since the EMI measures only need to    be taken at the multilayer module board 300.-   (6) The four connector terminals 310 provided as separate members,    which are mounted at the transfer adapter 400, are soldered onto the    board 300. As a result, the ease of operation such as positioning    while the connector terminals 310 are bonded onto the board 300    improves.-   (7) When soldering the four connector terminals 310, the positions    of the connector terminals 310 are controlled by placing the    position control inclined surfaces 314 of the adjacent connector    terminals 310 in contact with each other while the aligning pins 313    of the connector terminals 310 are loosely fitted at the positioning    holes 306 of the multilayer module board 300. As a result, the    connector terminals 310 are positioned with a high degree of    reliability.-   (8) Since the module board 300 is connected to the base board 200    through soldering together with other electronic components, the    number of module assembly steps does not need to increase.

INDUSTRIAL APPLICABILITY

While an explanation is given above in reference to the embodiment on anexample in which the present invention is adopted in a circuit boarddevice for an on-vehicle navigation system, the circuit board deviceaccording to the present invention may be adopted in conjunction with aportable navigation system or any other type of information apparatus.In addition, the embodiment explained above simply represents an exampleand the present invention may be adopted in a circuit board deviceachieved in any of various modes without being subject to anyrestrictions set forth in the embodiment. For instance, the use of atransfer adapter, connector terminals or a multi-chip module is notessential to the implementation of the invention. The types oflow-frequency electronic components and high-frequency electroniccomponents, too, are not limited to those used in the embodiment.

1. A circuit board device for an information apparatus comprising: abase board having mounted thereupon a plurality of low-frequencyelectronic components; and a multilayer module board mounted at onesurface of the base board and having mounted thereupon a plurality ofhigh-frequency electronic components including at least a CPU and amemory, wherein: the multilayer module board is one of (i) a low-endmodule board, (ii) a high-speed module board that operates at higherspeed than the low-end module board or (iii) an advanced function moduleboard having more functions than the low-end module board; and the baseboard is configured to accept interchangeably a connection with amultilayer board that is (i) the low-end module board, (ii) thehigh-speed module board and (iii) the advanced function module board,the plurality of high-frequency electronic components including a CPUand a memory mounted at, at least, a surface thereof, the plurality ofhigh-frequency electronic components are connected with one anotherthrough a wiring patterns formed at an inner layer thereof, and anoverall shape of the multilayer module board is rectangular and themultilayer module board comprises four connector terminals provided asseparate members each soldered onto one of four peripheral edgesthereof.
 2. A navigation system comprising a circuit board device for aninformation apparatus according to claim
 1. 3. The multilayer moduleboard according to claim 1, wherein: the four connector terminals eachinclude a narrow, elongated base portion constituted of resin and aplurality of pins fixed to the base portion; and the four connectorterminals are each carried with the base portion attached to a transferadapter and the four connector terminals are connected through solderingonto a rear surface of the board while attached to the transfer adapter.4. The multilayer module board according to claim 1, wherein: the fourconnector terminals each include a narrow, elongated base portionconstituted of resin; a plurality of pins fixed to the base portion;aligning pins projecting at both ends of the base portion to be usedwhen soldering the connector terminal onto a rear surface of the board;and inclined surfaces for position control formed at both ends of thebase portion to be used when soldering the connector terminal; a pair ofpositioning holes at which the aligning pins are loosely fitted areformed at each of four corners of the board; and positions of theconnector terminals are controlled when soldering the connectorterminals as the inclined surfaces for position control at adjacentconnector terminals come into contact with each other while the aligningpins are loosely fitted at the positioning holes.
 5. A circuit boarddevice, comprising: a base board; and a multilayer module board mountedon the base board, the multilayer module board comprising: a pluralityof high-frequency electronic components including a CPU and a memorymounted at, at least, a surface thereof, wherein: the plurality ofhigh-frequency electronic components are connected with one anotherthrough a wiring pattern formed at an inner layer thereof; an overallshape of the multilayer module board is rectangular and the multilayermodule board comprises four connector terminals provided as separatemembers each soldered onto one of four peripheral edges thereof; thefour connector terminals each include a narrow, elongated base portionconstituted of resin and a plurality of pins fixed to the base portion;and after the four connector terminals are each carried with the baseportion attached to a transfer adapter, the four connector terminals areconnected through soldering onto a rear surface of the board whileattached to the transfer adapter.
 6. A circuit board device, comprising:a base board; and a multilayer module board mounted on the base board,the multilayer module board comprising: a plurality of high-frequencyelectronic components including a CPU and a memory mounted at, at least,one surface thereof, wherein: the plurality of high-frequency electroniccomponents are connected with one another through a wiring patternformed at an inner layer thereof; an overall shape of the multilayermodule board is rectangular and the multilayer module board comprisesfour connector terminals provided as separate members each soldered ontoone of four peripheral edges thereof; the four connector terminals eachinclude a narrow, elongated base portion constituted of resin; aplurality of pins fixed to the base portion; aligning pins projecting atboth ends of the base portion to be used when soldering the connectorterminal onto a rear surface of the board; and inclined surfaces forposition control formed at both ends of the base portion to be used whensoldering the connector terminal; a pair of positioning holes at whichthe aligning pins are loosely fitted are formed at each of four cornersof the board; and positions of the connector terminals are controlledwhen soldering the connector terminals as the inclined surfaces forposition control at adjacent connector terminals come into contact witheach other while the positioning pins are loosely fitted at thepositioning holes.